Steel Wheels: Steel Industry Reveals Light Truck Wheel Innovation

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Steel Industry Reveals Light Truck Wheel Innovation

 

The Wheels Task Force of American Iron and Steel Institute has initiated a study on light truck wheels with the objective of creating a lightweight, affordable, attractively styled wheel for the light truck market. The target is a 17 percent reduction in mass.

The Task Force, which has representatives from steel companies, wheel manufacturers, wheel trim suppliers and OEMs, continues to work closely with automakers who seek reduced weight without sacrifice to appearance, performance, safety and affordability.

This project follows previously successful initiatives by the Wheels Task Force in 1998 dealing with the lightweight microalloy steel wheel. The wheel is a 15 x 6 passenger car wheel that is fully competitive with cast aluminum wheels in appearance and weight, offering a weight saving of 27 percent, compared to conventional steel wheels.

Additionally, the microalloy steel wheel is up to 11 percent lighter and 18 percent less costly than cast aluminum wheels. Permanent trim provides attractive styling that is competitive in appearance to aluminum wheels. Microalloy steel is a high-strength steel in which strength is achieved through additions of alloying elements such as columbium and vanadium.

For the current truck wheel project, the Task Force selected the Dodge Ram full-face 16x7 wheel as a benchmark for a two-phase study to prove out its targeted 17 percent weight reduction. The current full-face steel wheel weighs 29.6 pounds, while the current cast aluminum option wheel weighs 23.3 pounds.

A prototype wheel is spun using flow forming technology.

PHASE I

In Phase I of the project, the Task Force worked with Hayes-Lemmerz International Inc. to build prototypes using flow forming technology for the rims, a technique never before used for steel rims on light truck wheels. This process involves rotating the rim on a mandrel and using a forming tool, moving metal from one location on the rim to another, which results in variable rim thickness.

Both the rim and disc steel grades remained unchanged from the current production benchmark wheels.

The Phase I results are impressive. The wheel weight was reduced by 2.74 pounds to 26.86 pounds, or 9.3 percent.

PHASE II

Once again, the Wheels Task Force is collaborating with Hayes-Lemmerz to target further weight reduction for the light truck wheel through:

  • The substitution of microalloy steel for mild steel in the rim (70 ksi tensile strength steel replacing 50 ksi tensile strength steel);

  • The use of higher tensile strength microalloy steel in the disc (85 ksi for the microalloy versus 70 ksi steel); and once again,

  • The use of flow forming technology on the rim.

The Task Force expects to reduce the Phase II wheel weight to just 24.5 pounds, only 1.2 pounds heavier than the cast aluminum benchmark wheel on the Ram.

"The successful completion of Phase II will result in a steel wheel for light trucks that is comparable in weight to a cast aluminum wheel, but more economical," explains Chuck Gregoire, chairman of the Wheels Task Force. "The addition of permanent trim will yield an appearance every bit as attractive as aluminum wheels."

The Task Force completed this project in 2001.